This invention relates to gasoline dispensing nozzles for dispensing gasoline into vehicle fuel tanks, and more specifically to an attitude control valve for preventing vapors in the underground storage tanks from being displaced back into the atmosphere in those nozzle assemblies which have a system for receiving the vapors displaced from a vehicle gasoline tank.
Current environmental regulations will require in some areas that gasoline vapors displaced from a vehicle fuel tank while being filled are to be recovered in order to prevent their escape into the atmosphere. Many of the nozzle assemblies designed to meet this arrangement have a system for receiving the vapors displaced from the fuel tank and storing them in the underground hydrocarbon storage tanks.
To operate effectively, such a system should have several qualifications. First, the nozzle should fit substantially all the gasoline tank fillpipes for the vehicles currently in use and have a vapor receiving apparatus which forms a tight seal against the fillpipe so as to minimize the escape of hydrocarbons into the atmosphere. A second requirement is that the line from the vapor collecting apparatus to the underground storage tanks must have some type of control system to prevent the vapors in the underground tanks from being displaced into the atmosphere through the vapor receiving apparatus on the nozzle when the underground tanks are filled. A third requirement is that an interlock system be provided which prevents the gasoline nozzle from operating until the seal against the fillpipe is made.
Compliance with these requirements preferably should be accomplished by a design which requires minimum assistance by the service station operator, and also permits manual overriding of the interlock system for use on an unusual fillpipe design which does not permit full insertion of the dispensing nozzle. Also, the entire nozzle design should be simple to operate, light enough for use in self-service stations, and not require excessive force to make the seal to the fillpipe.
One method for preventing the escape of vapors from the underground tanks and into the atmosphere through the vapor receiving system is to make a seal at the end of the vapor receiving chamber which contacts the fillpipe when the nozzle is not in use. This method usually requires the use of a strong spring to extend the vapor receiving chamber against a ring on the discharge spout, which in turn requires excessive force to compress the chamber when the discharge spout is inserted into the fillpipe. Another problem with such a system is that when the nozzle is stored in the side of a pump, the chamber can be pressed away from the ring and break the seal. Preferably, a control valve should be used which will remain closed when the nozzle is not in use and should be designed to form a tighter seal when the pressure in the underground tanks increases.